Solvent proof marking for conduits



May 15, 1956 R. BATTLE ETAL 2,745,436

SOLVENT PROOF MARKING FOR CONDUITS Filed Oct. 5 1950 @ill `1 JNVENTORS @cH/4,2@ 547/25 AM@ By @uw i aN/vfe.

United States Patent O SOLVENT PROF MARKING FOR CONDUITS Richard Battle and Ralph E. Donner, West Los Angeles, vCalif., assignors to Douglas Aircraft Company, Inc.,

Santa Monica, Calif.

Application'October 3, 1950, Serial No. 188,252

6 Claims. (Cl. 138-47) vThis invention relates to means for identifying conduits, as for enabling selection of an individual conduit from a network of otherwise identical conduits, and nds particular utility in providing a substantially permanent identification marking for conduits, and for conduit sheaths.

Although the invention will hereinafter be described in connection with its use for identifying electrical conduits, it will become apparent that the invention is equally well adapted for employment with conduits conveying other media than electrical energy, provided the outerymost insulating sheath or layer on the conduit is of a the actinic rays of the sun, corrosive materials, and solvents as to be illegible.

The present invention provides a marking for such conduits which is substantially permanent in nature and is substantially completely resistant to most solvents and corrosives, to weathering, to ester compounds of the type used in synthetic hydraulic fluids, one of such liuids being known as Skydrol, and to substantially all reactive agents except alcohols, sulphuric acid and aqua regia.

To achieve these and other ends, broadly described,

the conduit resulting from the use of the present invention comprises a supporting core, such as a conductor wire, bearing on at least a part of its periphery an outermost layer of an organic, synthetic plastic which includes an identifying configuration comprising an indentation yespecially conformed to a predetermined code, the indentation being at least partially filled with a homogeneous admixture of a fusible, organic synthetic thermoplastic, and a pigment integrated by heat and pressure With the fused surfaces of the core that define the indentation.

In many cases, the outermost layer on the conduit will consist of a light-colored thermoplastic, such as one of the uncolored nylons, in which event the thermoplastic on the tape will consist of one of the nylons, the pigment then employed being a dark pigment, such as carbon black or some other amorphous carbon.

However, the invention contemplates, when the outermost layer on the conduit is a dark-colored nylon, or a light-colored nylon admixed with a dark pigment, that a light-colored thermoplastic, such as a light-colored nylon, be employed with a light-colored pigment, such as titanium dioxide and a binder, to mark the conduit.

The invention also provides novel marking material to aidin achieving these and other ends, the material consisting of. a marking-material transfer web comprising 2,745,436 Patented May 15, v1956 a flexible backing bearing, on the one face thereof, a layer consisting of a transferrable, homogeneous mixture of a pigment such as an amorphous carbon or titanium dioxide, and an organic synthetic plastic, such as a nylon, fusible together into the fusible thermoplastic of the conduit. The invention contemplates that the organic synthetic plastic on the tape be a thermoplastic which is cohesive and non-disintegrative at temperatures of the order of 400 F. and which will weld or fuse with a similar thermoplastic at the stated temperature. Examples `of such thermoplastics are the polyamides, including the nylons, and the fluorocarbons such as the polytrifluorochloroethylenes. The invention contemplates that the amorphous carbon may consist of carbon black and that the nylon, when such is admixed with it, be any condensation product of cyclohexanol with adipic acid that has a moisture or wetting resistance factor lying between about .44 and about 12.5. t also contemplates that the vnylon on the transfer web may be either an amorphous mass of nylon melted onto the web, or solvent flowed thereonto, or Du Pont type 6Y8 of nylon, or pulverulent or powdered nylon of the type employed for extrusion formingor powder-molding of objects out of nylon, and sprayed or dusted thereonto.

The invention also involves a novel method of forming the identification configuration on the organic synthetic thermoplastic coating of the conduit. Essentially, the method consists of establishing surface contact between a predetermined fusible surface area on the conduit and a predetermined area of the marking material on the surface of the novel transfer web; pressurally applying a marking instrumentality in opposition to said area on the web sufficiently forcefully to at least initiate transference of the marking material to the conduit in a localized deposit of predetermined contour conforming to that of the marking instrumentality and constituting a homogeneous actinism, corrosion, and dissolution resistant mass; maintaining the pressure and applying suflicient heat to at least one of said contacting surfaces for a period of time adequate to fuse the transferable material into the subadjacent fused material constituting the outer layer of the conduit; and separating the conduit, the marking material and the marking instrumentality.

Typical forms of the transfer web, and the marked wire are shown in the accompanying drawings and described hereinafter Vin conjunction with these drawing but merely to exemplify the invention, as they do not constitute the sole forms the invention may take.

In thesedrawings:

Figure l is a longitudinal sectional View of the simplest form of the novel transfer web or tape;

Figure 2 is a similar View of a still more advantageous form of the tape, and

Figure 3 is a fragmentary longitudinal sectional View of an insulated electrical conductor bearing the indelible indicia produced by the invention.

The present method can actually be performed satisfactorily by a series of hand operations involving merely the wire to be marked resting on an anvil, a tape fed transversely across the wire at longitudinally spaced intervals of the wire and a marking press head reciprocable by hand downwardly upon the upper surface of the tape, they printing indicia of the press head being surrounded by a suitable heating coil. The present method can also be performed by many suitable types of automatic apparatus. VIn any event, it is essential to the performance of the invention that the novel transfer web shown in Figures 1 and 2 be employed in fusing marking material into the outer fusible thermoplastic layer of the electrical conduit.

The transfer web, in its simplest form,.,as shown rin Figure 1, essentially comprises a flexible heat resistant tough backing or base layer 10, here shown as a ribbon of cellophane, coated on its one face with a heat separable parting layer 11. This heat responsive parting layer preferably is of such a nature as to be releasable from the cellophane and to release any material carried on its outer face, such as the printing material hereinafter disclosed. It can, however, be of such a nature as to itself remain adhered to the cellophane backing. One such suitable parting layer consists of a film of the order of .0001 inch thick and composed of a wax compound, ozokerite, which is a natural mineral wax. However, any other wax which will perform the aforesaid functions and has a melting point of the order of 400 F., which is the critical printing temperature of this invention, is also suitable.

On the outer face of layer 11 is a dispersion 12 in the form of a film of the order of .0001 to .0003 of an inch thick and consisting of a pigment 13 which preferably consists of an amorphous carbon or other dark pigment l employed when the outer coating of the wire to be marked is a clear nylon; a binder 14 and any suitable form of condensation product of cycloheXanol and adipic acid, such as one of the Du Pont type 6 or S nylons, 15. The nylon may be in the flake condition, the extiusive powder condition, or the amorphous bulk condition and may be flowed onto the carbon black and binder, rst applied, in an alcoholic solution or may be melted thereonto or sprayed or dusted thereonto. In any event, the nylon is admixed homogeneously with the carbon black and the binder thereof, which may consist of a thermoplastic resin, in a black, homogeneous, thin film of transferable marking material fusible into the thermoplastic outer coating of the wire. The invention, as aforestated, contemplates that the predetermined transferable area of the transfer web be transferred by pressure and heat of the order of 400 F.

In the form of tape shown in Figure 2, the nylon 15 of the transferable layer 12A is, before being applied to the carbon black and binder previously applied to the wax layer, or concurrently with such application, admiXed with an alcohol-soluble, fast, spirit dye 16 such as the fast-blue dye sold by Braun Chemical Company, Los Angeles, California, the dye rst having been admixed with butanol and ethanol. The composition of this layer is otherwise the same as that of layer 12 in Figure l. The admixture is preferably made in the following manner and proportions:

For one gallon of resultant, dissolve 1A ounce of the dye in one pint of butanol. A gallon of nylon solution, marketed by the Deville Laboratories of Glendale, California, as F. T. H. A., is then stabilized and rendered non-jelling at 100 F. to 110 F. for 15 to 30 minutes until any gel is dispersed into a yellowish transparent liquid. One pint of this dye-stabilized nylon is removed from the gallon and returned to stock. The dye dissolved in the butanol is added to the remaining 7 pints of stabilized nylon. The mixture is stirred thoroughly and strained for application by flowing onto the carbon black and binder already applied to the wax layer, or owed on concurrently therewith, producing the tape shown in Figure 2.

Although the description hereinabove refers to the employment of the alcohol soluble fast spirit dye made by the Braun Company as a specific form of nylon stabilizing compound, it is to be understood that any other suitable stabilizer is contemplated by the invention for use with the nylon as a stabilizer thereof, particularly when the nylon is one other than the F. T. H. A. referred to hereinabove. It is to be understood that the invention also contemplates the use of any nylon, that is, any condensation product of cyclohexanol with adipic acid, other than the above mentioned nylon and regardless of its mode of application to the tape, provided it has a moisture resistance or wetting resistance factor lying between the limits of .44 to 12.5.

As mentioned above, the tape may be employed in any suitable form of apparatus for carrying out the present method to indelibly mark electrical and other conduits, and the invention is also capable of being performed in a series of manual operations, the method in any event essentially consisting of establishing surface contact between a predetermined fusible surface area of the fusible, organic synthetic thermoplastic outermost sheath on the conduit and an independent transferable and fusible predetermined area, as on a tape, the area transferred consisting essentially of a pigment and binder and a fusible organic synthetic plastic homogeneously admiXed; pressurally applying a marking instrumentality in opposition to said transferable area sufficiently forcefully to effect initiation of transference of the pigment, binder and the plastic to said article in a homogeneous, corrosion and dissolution resisting, localized deposit conforming to the conformation of the contacting area of the marking instrumentality; maintaining said pressure and applying suicient heat to at least one of said contacting surfaces for a period of time adequate to fuse the transferable material into the fused area on the outermost surface of the conduit; and separating the marked object, the independent area, and the marking instrumentality.

A longitudinal section of a fragment of an insulated electric conductor indelibly marked by the present method, apparatus and tape is shown in Figure 3. The particular electrical conductor chosen to illustrate the invention includes a metallic wire forming its core, which core is immediately surrounded by a sheath 91 of B-2 Vinylite. Surrounding this sheath is a sheath of Fiberglas 92 which is immediately surrounded by a sheath 93 of A-l0 Vinylite. The outermost sheath 94 of the wire consists usually of a clear or light colored nylon such as Du Pont FM-3003 or F-1000 nylon, produced by the E. I. Du Pont de Nemours & Company of Wilmington, Delaware. In this outermost sheath is an indentation formed by the method and means of the present invention and conformed to a predetermined code or identiiication system, the indicia usually consisting of numerals. This indentation is hollow and has welded or fused with its walls a hollow layer or liner 95 constituting the indicia and consisting of the materials on the outermost layer of the tape and at least a portion of the layer of the parting wax. Because of the adherence of the adjacent portions 96 of the fused nylon sheath to the cellophane lm heated by the hot printing type, as the latter is withdrawn the wires nylon sheath around these indentations is raised a slight distance above the general level of the outer surface of the nylon sheath.

In the case where the most advanced form of the novel tape is employed in the method and apparatus of the invention, the liner 95 consists of a homogeneous admixture of carbon black, a thermoplastic resin binder, a nylon homogeneously dispersed therein and having a wetting-resistance factor varying from .44 to 12.5 and, as a nylon dispersion stabilizer, an alcohol-soluble, fast, spirit dye, such as the fast blue produced by the Braun Company. This liner is substantially indelible, being substantially permanently resistant to actinicism, corrosion, and dissolution by any solvent except the alcohols, sulphuric acid and aqua regia.

Because of the resistance of the marking material to actinic rays it is not at all likely that the marked indicia will fade when exposed to weathering and since the marking material is welded and fused into integrality with the nylon sheath of the wire, it is unlikely that the indicia will be loosened out or drop out during service. It is also unlikely that the markings will be dissolved or washed out upon exposure to any of the solvents commonly found in industrial plants and in aircraft and these markings are particularly resistant to such ester compounds as the hydraulic uid known as Skydrol, a tradename owned by Monsanto Chemical Company, St. Louis, Missouri.

When the nylon in the sheath on the wire is, for purposes of specific resistance to specific agents, admixed with a dark colored solvent resisting material, the present invention contemplates imprinting visible indicia thereon in material from the tape that will contrast to the dark colored wire sheathing. In this event, the carbon black in the outermost film on the tape is replaced by a light colored pigment such as titanium dioxide or the like, the outermost film on the tape otherwise remaining the same in composition and mode of action and use in the process and apparatus. The titanium dioxide is usually suh'iciently light colored to effect a visible contrast with the dark colored wire sheath when imprinting thereon to render the indicia plainly visible. The outermost layer on the tape has, as aforestated, a film thickness of the order of .0001 to .0003 inch and the indentation has a depth of the order of 14,4 inch. The distance between the top of the marking material and the adjacent surface of the nylon sheath on the wire is of the order of 17428 of an inch, the thickness of the deposit thus being of the order of lAgS of an inch. Notwithstanding that the film thickness of the marking material is of the order of only .0001-.0003 of an inch, the thickness of the deposit, at least in the bottom of the indentation is many times greater than .0001 of an inch and usually of the order of .0005 of an inch, because of the concentration in the bottom of the indentation of the surface coating over a wide area of tape pushed together into the bottom of the indentation and because of the coating of wax deposited therewith from the parting layer on the tape.

Although the organic synthetic thermoplastic employed in the outermost layer of the tape has been described as a condensation product of cyclohexanol with adipic acid, and preferably a nylon, the invention contemplates that the nylon, both in the tape and in the outer sheath 'of the wire, may be replaced by a fluorocarbon such as polytrifluorochloroethylene, found on the market as Kel-F, a trade name of the M. W. Kellog Company, 225 Broadway, New York city, or Teonf a tetrafluorochloroethylene, produced by E. I. Du Pont de Nemours & Company. at Arlington, New Jersey.

Although certain specific proportions and dimensions have been mentioned by way of example and clarification, it is to be understood that the invention itself is not in any Wise limited thereby and can be performed in any manner lying within the scope of the annexed claims.

We claim:

l. An indexed article in which the indicium is resistant to stress and is substantially corrosion, actinicism, erosion and solvents-proof, comprising: a substantially exible core member having a flexible thermoplastic sheath, said sheath having a sunken portion therein in the form of a bas-relief indicium, the relief portion of said indicium being bare and exposed and consisting essentially of a visible coalescence of materials substantially inert to corrosion, actinicism, erosion and commercial solvents, the coalesced materials of the relief-portion being integral and in one piece with the thermoplastic walls of said sunken portion in said sheath so as to preclude stress-disintegration of said relief and release thereof from said sheath under flexure, torsional compression and shear stresses in said article.

2. An indexed article in which the indicium is substantially proof against all forces and influences to which the article is normally subjected, comprising: a core member having a thermoplastic sheath, said sheath having a sunken portion lying generally radially inwardly of the general exterior surface of the article, the bottom of said sunken portion bearing a bas-relief indicium integral therewith and projecting only slightly radially outwardly from said bottom, the projecting portion of said bas-relief consisting essentially of a common solvents, actinicism, erosion, and corrosion resistant coalescence of a substantially inert pigment with a substantially inert fusible organic synthetic plastic.

3. An indexed article in which the indicium is substantially proof against all forces and influences to which the article is normally subjected, comprising: a core member having a thermoplastic sheath, said sheath having a sunken portion lying generally radially inwardly of the general exterior surface of the article, the bottom of said sunken portion bearing a bas-relief indicium integral therewith and projecting only slightly radially outwardly from said bottom, the projecting portion of said bas-relief consisting essentially of a common-solvents, corrosion, erosion, and actinicism-resistant coalescence of an amorphous-carbon pigment with a nylon.

4. An indexed article in which the indicium is substantially proof against all forces and influences to which the article is normally subjected, comprising: a core member having a thermoplastic sheath, said sheath having a sunken portion lying generally radially inwardly of the general exterior surface of the article, the bottom of said sunken portion bearing a bas-relief indicium integral therewith and projecting only slightly radially outwardly from said bottom, the projecting portion of said bas-relief consisting essentially of a coalescence of a substanitally inert thermoplastic resin binder; a substantially inert thermoplastic resin binder; a substantially inert thermoplastic nylon dispersed therein; and an inert amorphouscarbon pigment.

5. The combination with an elongate core-member bearing a Vinylite casing in contact with same, the casing being enclosed in a Fiberglas sheath, the latter in turn being encased in another Vinylite sheath; of an outermost nylon sheath contacting said another Vinylite sheath, having at least a portion of its surface sunken in the form of a bas-relief indicium, the relief-portion of said indicium being bare-faced and exposed to view; said relief portion lying sufficiently far below, or inwardly of, the outer, or peripheral surface of the sheath as to substantially preclude abrasion-effected deterioration of the indicium.

6. A durably indexed article having a substantially permanently legible indicium therein, comprising: a core member having a sheath of a composition and thickness normally abradahle to a predetermined extent in the course of the service-life of said article, said sheath having a portion thereof sunken as a bas-relief, the relief portion of said bas-relief being of a color contrasting to said sheath and constituting the indicium and being composed of a plurality of solvent and corrosion-proof materials, most of said materials being of a composition extraneous to that of the sheath; said relief-portion being in fused, substantially monolithic-like integration with the sheath; said relief portion having the general plane of its outer surface lying so far below the surface of the sheath as to substantially preclude abrasion of said reliefportion into illegibility in the course of the service-life of said article.

References Cited in the le of this patent UNITED STATES PATENTS 2,159,693 Gaylord, Jr. May 23, 1939 2,186,788 Olson Jan. 9, 1940 2,232,846 Freydberg Feb. 25, 1941 2,235,514 Brown Mar. 18, 1941 2,240,058 Stover Apr. 29, 1941 2,510,750 Marquardt .Tune 6, 1950 2,516,751 Brown July 25, 1950 2,521,992 Nielson Sept. 12, 1950 FOREIGN PATENTS 387,789 Great Britain Feb. 16, 1933 401,529 Great Britain Nov. 16, 1933 591,647 Great Britain Aug. 25, 1947 

1. AN INDEXED ARTICLE IN WHICH THE INDICIUM IS RESISTANT TO STRESS AND IS SUBSTANTIALLY CORROSION, ACTINICISM, EROSION AND SOLVENT-PROOF, COMPRISING: A SUBSTANTIALLY FLEXIBLE CORE MEMBER HAVING A FLEXIBLE THEREMOSPLASTIC SHEATH, SAID SHEATH HAVING A SUNKEN PORTION THEREIN IN THE FORM OF A BAS-RELIEF INDICIUM, THE RELIEF PORTION OF SAID INDICIUM BEING BARE AND EXPOSED AND CONSISTING ESSENTIALLY OF A VISIBLE COALESCENCE OF MATERIALS SUBSTANTIALLY INERT TO CORROSION, ACTINICISM, EROSION AND COMMERCIAL SOLVENTS, THE COALESCED MATERIALS OF THE RELIEF-PORTION BEING INTEGRAL AND IN ONE PIECE WITH THE TERMOPLASTIC WALLS OF SAID SUNKEN PORTION IN SAID SHEATH SO AS TO PRECLUDE STRESS-DISINTETRATION OF SAID RELIEF AND RELEASE THEREOF FROM SAID SHEATH UNDER FLEXURE, TORSIONAL COMPRESSION AND SHEAR STRESSES IN SAID ARTICLE. 